1. Field of the Invention
This invention relates to a control apparatus and a control method for a hybrid vehicle in which an engine and a motor are installed as motive power sources.
2. Description of Related Art
In the related art, there are hybrid vehicles called as one-motor or two-motor vehicle depending on the number of motors functioning as motive power sources installed in the vehicle, and it is a common technique to configure the motor to exercise an electricity generating function. As one example of a one-motor vehicle, Japanese Patent Application Publication No. 2008-179263 (JP 2008-179263 A) discloses a vehicle provided with an engine, a motor having an electricity generating function, and an electric generator which generates electricity by motive power output by the engine, wherein electricity is generated by the electric generator by motive power output from the engine, and this electric power is supplied to the motor, whereby a motor torque is output from the motor and transmitted to drive wheels as a drive torque. Moreover, J P 2008-179263 A discloses generating electricity by the motor through regeneration control of the motor, if an abnormality has occurred in the electric generator.
Furthermore, examples of the configuration of a two-motor vehicle are disclosed in Japanese Patent Application Publication No. 2008-279886 (JP 2008-279886 A) and Japanese Patent Application Publication No. 08-295140 (JP 08-295140 A). JP 2008-279886 A and JP 08-295140 A disclose configurations provided with an engine, two motors that are sources of motive power, and a power split mechanism formed from a planetary gear mechanism in which three rotating elements move differentially, wherein, in the power split mechanism, any one of the rotating elements is coupled to the engine, a further rotating element is coupled to the first motor, and yet a further rotating element is coupled to drive wheels and the second motor. In other words, the motive power output by the engine is divided and transmitted to the first motor side having an electricity generating function and an output member side coupled to drive wheels, by a power split mechanism. Furthermore, due to a reactive force generated by the first motor, it is possible to control the number of revolutions of the engine, as appropriate, in accordance with the number of revolutions of the first motor.
In particular, in the configuration disclosed in JP 08-295140 A, the engine torque is inputted to a carrier of the power split mechanism via an output shaft, and a clutch for mechanically disengaging the output shaft and the engine, and a one-way clutch which stops rotation of the carrier by fixing the output shaft, are provided, in such a manner that the reactive force of the torque produced by the first motor is received by a torque produced by the one-way clutch. Moreover, JP 08-295140 A also indicates that, when the vehicle is travelling by the motive power of the first motor and the second motor, the clutch is released and therefore the engine does not need to be stopped.